1. Technical Field
The present invention relates to an access panel assembly, and more particularly to such a panel assembly with an improved gasket means particularly adapted for use in conjunction with aircraft wing fuel tanks.
2. Background Art
It is quite common in present day aircraft for fuel tanks to be mounted in the wing of the aircraft. Quite commonly, the bottom side of the fuel tank has a removable access panel that is mounted flush with the lower wing surface. Such access panels are removed periodically for such things as inspection, cleaning the fuel tank, etc.
There are a number of special design considerations associated with such access panels. Obviously, the panel should form a reliable seal to prevent leakage from the fuel tank, and it should be lightweight and of adequate structural strength to be consistant with overall objectives for aircraft design. A further and possibly more subtle consideration is that the wing of the aircraft will deflect upwardly and downwardly under varying aerodynamic loads, and there will accordingly be some flexing of the structural components of the wing. This will in turn affect the design of the attachment of the panel to the wing structure.
Yet another consideration relates to the electrical conductivity of the aircraft structure. Because of the possibility of lightning strikes, it is desirable that metal components of the aircraft have a conductive path to other metallic parts of the aircraft. However, if such components are to be joined one to another so that there is metal to metal contact, there is a possibility of a resultant unwanted wear and possible corrosion.
A common prior art arrangement for such a panel is to have a main panel member with a periperhal edge portion that fits inside the edge portion of the wing structure that defines the access opening. There is a clamp ring which fits against edge portions of the panel and against the wing structural edge portion that defines the opening, and there are a number of fasteners which press the clamp ring into firm engagement with the panel edge portions and the wing structure edge portion. A suitable fuel seal is provided. Also, a metal mesh annular gasket is positioned between the clamp ring and the panel and wing edge portions which are in bearing engagement with the clamp ring. The gasket is commonly impregnated with a grease or other suitable lubricant to alleviate problems of abrasion with regard to the gasket and also the bearing surfaces which come into engagement with the gasket.
While the prior art designs for such panel assemblies have in general been adequate, there is a continued need for design improvement with regard to simplifying and reducing service, requirements, proper containment of lubricant, prevention of corrosion that might result from abrasion or other causes, and other considerations. Accordingly, it is an object of the present invention to provide an improved panel assembly particularly adapted for use in connection with an aircraft wing fuel tank, an improved gasket designed for use in such an assembly, and an improved process for making such a gasket.